Inputs

Network data

Files with the prefix ampl_ contain the data and the parameters of the network on which the reactive OPF is executed.

These files are obtained by using the V3 of the extended version of PowSyBl AMPL export, which is the default version.

Note that from release 0.10.0 of OpenReac, the active target of VSC and LCC converter stations is calculated using HVDC line active set point and the converter mode, both specified in ampl_network_hvdc.txt. The losses related to rectifier/inverter conversion, and HVDC line are ignored.

Configuration of the run

The user can configure the run with the dedicated Java interface (see OpenReacParameters). Specifically, the user can set various parameters and thresholds used in the preprocessing and modeling of the reactive OPF. These are specified in the file param_algo.txt:

Parameter	Description	Java default value	Domain
log_level_ampl	Level of display for AMPL prints	INFO	{DEBUG, INFO, WARNING, ERROR}
log_level_knitro	Level of display for solver prints (see AMPL documentation)	\(1\)	{0, 1, 2}
objective_choice	Choice of the objective function for the ACOPF (see AC optimal powerflow)	\(0\)	{0, 1, 2}
ratio_voltage_target	Ratio to calculate target V of buses when objective_choice is set to \(1\) (see AC optimal powerflow)	\(0.5\)	\([0; 1]\)
coeff_alpha	Weight to favor more/less minimization of active power produced by generators or deviation between them and target values (see AC optimal powerflow)	\(1\)	\([0; 1]\)
penalty_invest_rea_pos	Weight of the positive reactive slack penalty term in the ACOPF objective (see AC optimal powerflow)	\(10\)	\(\mathbb{R}^{+}\)
penalty_invest_rea_neg	Weight of the negative reactive slack penalty term in the ACOPF objective (see AC optimal powerflow)	\(10\)	\(\mathbb{R}^{+}\)
penalty_active_power	Weight of the active power generation term in the ACOPF objective. If left unset, resolved at export to \(1\) when objective_choice \(=0\), and \(0.01\) otherwise (see AC optimal powerflow)	objective-dependent (\(1\) or \(0.01\))	\(\mathbb{R}^{+}\)
penalty_units_reactive	Weight of the reactive power of units term in the ACOPF objective (see AC optimal powerflow)	\(0.1\)	\(\mathbb{R}^{+}\)
penalty_transfo_ratio	Weight of the transformer ratio term in the ACOPF objective (see AC optimal powerflow)	\(0.1\)	\(\mathbb{R}^{+}\)
penalty_voltage_target_ratio	Weight of the voltage target ratio term (Vmin/Vmax normalized target) in the ACOPF objective. If left unset, resolved at export to \(1\) when objective_choice \(=1\), and \(0.01\) otherwise (see AC optimal powerflow)	objective-dependent (\(1\) or \(0.01\))	\(\mathbb{R}^{+}\)
penalty_voltage_target_data	Weight of the voltage target data term (V0 input value targeting) in the ACOPF objective. If left unset, resolved at export to \(1\) when objective_choice \(=2\), and \(0.01\) otherwise (see AC optimal powerflow)	objective-dependent (\(1\) or \(0.01\))	\(\mathbb{R}^{+}\)
Pnull	Threshold of active and reactive powers considered as null	\(0.01\) (MW)	\([0; 1]\)
Znull	Threshold of impedance considered as null (see Zero impedance threshold)	\(10^{-5}\) (p.u.)	\([0; 0.1]\)
epsilon_nominal_voltage	Threshold to ignore voltage levels with nominal voltage lower than it	\(1\) (kV)	\(\mathbb{R}^{+}\)
min_plausible_low_voltage_limit	Consistency bound for low voltage limit of voltage levels (see Voltage level limit consistency)	\(0.5\) (p.u.)	\(\mathbb{R}^{+}\)
max_plausible_high_voltage_limit	Consistency bound for high voltage limit of voltage levels (see Voltage level limit consistency)	\(1.5\) (p.u.)	[min_plausible_low_voltage_limit; \(\infty\)]
ignore_voltage_bounds	Threshold to replace voltage limits of voltage levels with nominal voltage lower than it, by [min_plausible_low_voltage_limit; max_plausible_high_voltage_limit]	\(0\) (p.u.)	\(\mathbb{R}^{+}\)
buses_with_reactive_slacks	Choice of which buses will have reactive slacks attached in ACOPF solving (see AC optimal powerflow)	ALL	{CONFIGURED, NO_GENERATION, ALL}
PQmax	Threshold for maximum active and reactive power considered in correction of generator limits (see PQ unit domain)	\(9000\) (MW, MVAr)	\(\mathbb{R}\)
defaultPmax	Threshold for correction of high active power limit produced by generators (see PQ unit domain)	\(1000\) (MW)	\(\mathbb{R}\)
defaultPmin	Threshold for correction of low active power limit produced by generators (see PQ unit domain)	\(0\) (MW)	\(\mathbb{R}\)
defaultQmaxPmaxRatio	Ratio used to calculate threshold for corrections of high/low reactive power limits (see PQ unit domain)	\(0.3\) (MVAr/MW)	\(\mathbb{R}\)
minimalQPrange	Threshold to fix active (resp. reactive) power of generators with active (resp. reactive) power limits that are closer than it (see PQ unit domain)	\(1\) (MW, MVAr)	\(\mathbb{R}\)
default_variable_scaling_factor	Default scaling factor applied to all the variables (except reactive slacks and transformer ratios) before ACOPF solving	\(1\)	\(\mathbb{R}^{*,+}\)
default_constraint_scaling_factor	Default scaling factor applied to all the constraints before ACOPF solving	\(1\)	\(\mathbb{R}^{+}\)
reactive_slack_variable_scaling_factor	Scaling factor applied to all reactive slacks variables before ACOPF solving (see AC optimal powerflow)	\(0.1\)	\(\mathbb{R}^{*,+}\)
transformer_ratio_variable_scaling_factor	Scaling factor applied to all transformer ratio variables before ACOPF solving (see AC optimal powerflow)	\(0.001\)	\(\mathbb{R}^{*,+}\)
shunt_variable_scaling_factor	Scaling factor applied to all shunt variables before ACOPF solving (see AC optimal powerflow)	\(0.1\)	\(\mathbb{R}^{*,+}\)
optimization_after_rounding	Boolean to indicate if a 2nd ACOPF optimization should be conducted after rounding the transformer taps (see AC optimal powerflow)	false	{false, true}

Please note that for these parameters, the AMPL code defines default values which may be different from those in Java (for example, for the scaling values). This allows a user to use the AMPL code without going through the Java interface, and without providing the file param_algo.txt.

In addition to the previous parameters, the user can specify which parameters will be variable or fixed in the ACOPF solving (see AC optimal powerflow). This is done using the following files:

File	Description	Default behavior of modified values
param_transformers.txt	Ratio tap changers with a variable transformation ratio (real variable). Note that ratio tap changers on branches with one side open are not optimized.	Transformation ratios are fixed
param_shunt.txt	Shunts with a continuous variable susceptance and which can be modified and/or connected (only if possible bus is defined in ampl_network_shunts.txt)	Shunt susceptances are fixed
param_generators_reactive.txt	Generators with a constant reactive power production. If this value is not consistent (> PQmax), the reactive power production stays variable	Coherent reactive power productions (see P/Q unit domain) are variable
param_buses_with_reactive_slack.txt	Buses with attached reactive slacks if configurable parameter buses_with_reactive_slacks = “CONFIGURED”	Only buses with no reactive power production have reactive slacks attached

All of these files share the same format: 2 columns #”num” “id”.

Once again, the user can directly execute the AMPL code without passing these parameters files as input. If so, empty files will be created during execution.

Parallel transformers

The optimizer automatically detects groups of transformers connected in parallel and generates a file that is read as input by the AMPL code (see Parallel transformers for the resulting behavior). This file is derived from the detection only and is not provided by the user: it carries the topological membership of the bundles (every member of every orientable bundle) and each member’s orientation relative to the bundle’s canonical direction (+1: declared in the same direction as the bundle’s first member in id order, -1: declared in the opposite direction), while the qualification (tie / fix / relax) and all the effective ratio bounds are computed by the AMPL code from its own data. Unlike the parameter files above, it does not follow the #"num" "id" format:

File	Format (columns)	Description
param_parallel_transformers.txt	#num_bundle num_branch orientation id	Topological membership and orientation of the detected parallel bundles: all branches sharing a num_bundle are parallel, and orientation is +1 for a member declared in the bundle’s canonical direction, -1 for a member declared in the opposite direction. Whether a bundle is tied, fixed (single-point/empty intersection) or relaxed, together with all the effective per-unit ratio bounds, is derived by the AMPL code.

New voltage limits

In addition to the elements specified in section Configuration of the run, the user may choose to override the voltage limits of specified voltage levels. These values must be defined in ampl_network_substations_override.txt and are employed to establish the new voltage limits as specified in section Voltage level limit consistency.

Format of ampl_network_substations_override.txt: 4 columns
#”num” “minV (pu)” “maxV (pu)” “id”

When overriding the voltage limits, checks are also done to verify, for each voltage level, that “minV (kV)” and “maxV (kV)” are in the following range : \([0.85 * Vnom - 5, 1.15 * Vnom + 5]\)

If it’s not the case, reports are created to indicate the number of voltage levels concerned, and the detailed information for each of these voltage levels.